1. Field of the Invention
The present invention relates to a book binding apparatus in which imaged sheets are glue-bound as a book, and more particularly, it relates to a book binding apparatus which is applicable to an on-line system wherein a plurality of image forming apparatuses required for forming images on sheets successively, a book binding apparatus for bookbinding the sheets on which the images were formed and a sorting and containing apparatus for sorting and containing the bookbound sheet bundles are interconnected.
2. Related Background Art
In the past, when a plurality of sheets on which images were formed are automatically glue-bound to obtain a book, an on-line system wherein a plurality of apparatuses required for performing such jobs are interconnected has been used. For example, the on-line system includes a reading and sheet supplying apparatus comprising an original setting portion for setting an original, an optical system for scanning the original, and a sheet supplying apparatus for containing a number of sheets and for supplying the sheet; an image forming apparatus for forming an image on the sheet supplied from the sheet supplying apparatus; a book binding apparatus for bookbinding the sheets on which the images were formed; and a sheet sorting and containing apparatus for sorting and containing the bookbound or finished sheet bundles or the sheets. These apparatuses are interconnected in series.
When the sheet bundle is bookbound in the book binding apparatus, the sheet bundle aligned in a sheet align tray is glue-bound by a gluing binder. A bind tape used with the gluing binder is of hot melt type. The bind tape is abutted against the sheet bundle and is adhered to the sheet bundle by melting glue by means of a heater. Further, the sheets were contained in a single sheet align tray and were aligned with each other by abutting the sheets against an abutment member. The sheet bundle and the bind tape abutted against the sheet bundle were heated by a single tape heating apparatus. Further, a single stacker was provided in an apparatus for containing the finished sheet bundles.
However, in the conventional book binding apparatuses, it took a long time for melting the glue on the bind tape after the bind tape is set in the tape heating apparatus. Further, even when the molten bind tape abutted against the sheet bundle was heated, since the heat was absorbed by the sheet bundle, the bind tape could not adhered to the sheet bundle sufficiently. That is to say, it took a long time for heating the sheet bundle having the room temperature up to the gluing temperature. Further, the image forming apparatus of high speed type wherein a distance between supplied sheets is relatively short is used with the on-line system. Accordingly, when the single sheet align tray is used, since the sheets are successively supplied while the sheets in the tray are being aligned, the productivity of the system is worsened. In addition, as mentioned above, since it takes a long time for heating the sheet bundle, the productivity is further reduced.
Further, when the sheets entered into the sheet align tray are aligned with each other, if any sheet abutted against the abutment member is bounded away from the abutment member and the next sheet is rested on the bounded sheet, tip ends of the sheets cannot be aligned with each other, thereby causing the poor bookbinding. Further, when each sheet is double-folded or Z-folded, a trailing end of the sheet bundle rested on the sheet align tray is swelled, with the result that the next sheet is struck against the sheet bundle, thereby causing the poor sheet conveyance. Further, when the single stacker for containing the finished sheet bundles is used, in the case where a plurality of sheet bundles are bookbound, the finished condition of any sheet bundle cannot be ascertained until the bookbinding of all of the sheet bundles is completed, thus causing the inconvenience. That is to say, when an operator tries to draw the stacker to check the sample of the finished sheet bundle, the system must be stopped temporarily, thereby reducing the productivity.